[FEATURE] Add create comment result filter

[chaoticbear]

Overview

The goal of this PR is to add filters to the create comment results. These filters can be used to modify the result sent via webhook.

Our use case

• We're using wp-graphql as a backend for a mobile app
• wp-webhooks allows us to send webhooks when comments are created

Filtering the post result allows us to send graphql IDs to the app to allow it to to look up the notification post and parent comment via our wp-graphql endpoint.